A common problem associated with the use of firearms, especially automatic or semi-automatic firearms, is the inability of the user to easily and accurately determine the number of ammunition rounds remaining in the magazine or "clip" of the gun. In certain law enforcement and military situations for example, the law enforcement officer or soldier may need to know the precise amount of ammunition remaining in his or her weapon, or at the very least, that the number of rounds remaining is below some predetermined threshold. Also, gun enthusiasts and hunters have found a need and a desire for easily and accurately determining the number of live rounds of ammunition remaining in a weapon. A knowledge of the precise number of rounds remaining in a weapon, or an indication that live ammunition is present in the weapon is another safeguard to preventing accidental shootings.
Ammunition counting and display devices for firearms have been developed in an effort to provide law enforcement officers, military personnel, hunters, gun enthusiasts, and others with a mechanism for easily and accurately counting and displaying the number of rounds fired from a weapon, or the number of unfired rounds remaining in the weapon. However, none of these prior devices has proven to be satisfactory for accomplishing either of these tasks. These prior systems have generally been too complicated and have all required the firearm itself to be modified in some manner to accept the device. Many of the prior systems have required modifications to the grip, the slide mechanism, and the magazine mechanism of a weapon. Such modifications and complex installation requirements make it difficult and undesirable for many gun users to utilize these devices. Also, some of the prior devices add an unacceptable amount of bulk and weight to the firearm, resulting in a weapon that is more difficult to holster, aim, and fire.
Many of these prior ammunition counting systems utilize the movement of the slide mechanism of the firearm relative to the body of the firearm to count the number of times the weapon has been fired. There are several disadvantages to this approach. Any modification of the slide assembly, especially by a less experienced gun user, increases the likelihood of the slide assembly becoming jammed or otherwise malfunctioning. Also, these prior system that increment or decrement a counter based upon the movement of the slide necessarily require that the number of rounds initially present in the firearm is properly sensed or entered by the user. For example, one prior system assumes that the magazine will always be fully loaded when it is initially inserted into the weapon and therefore automatically sets the counter to "8" or some other predefined value. The counter is then decreased by "1" each time the slide moves relative to the gun body. It can be seen that should the magazine be loaded with less than eight rounds of ammunition when it is initially inserted in to the weapon, the number of rounds indicated on the display would be inaccurate, resulting in a dangerous and potentially deadly situation.
Another disadvantage with merely incrementing or decrementing a counter based upon movement of the slide mechanism is that should the device fail to properly sense the firing of the weapon, even once, the count will be inaccurate from that point on.